Patient Support Apparatus With Deck Section Actuator

ABSTRACT

A patient support apparatus for supporting a patient comprising a support frame and a support deck coupled to the support frame. The support deck has a deck section arranged to articulate relative to said support frame between a first position and a second position. An actuator is interposed in force-translating relation between the support frame and the deck section to articulate the deck section. The actuator comprises a biasing device configured to store mechanical energy and having an interface. The actuator further comprises a torque multiplier coupled to the deck section and engaged with the interface to translate mechanical energy stored in the biasing device into force acting on the deck section to urge the deck section toward the first position.

CROSS-REFERENCE TO RELATED APPLICATION

The subject patent application claims priority to and all the benefitsof U.S. Provisional Patent Application No. 62/609,032 filed on Dec. 21,2017, the disclosure of which is hereby incorporated by reference in itsentirety.

BACKGROUND

Patient support apparatuses, such as hospital beds, stretchers, cots,tables, wheelchairs, and chairs are used to help caregivers facilitatecare of patients in a health care setting. Patient support apparatusesgenerally comprise a base, a frame, and a patient support deck defininga patient support surface upon which the patient is supported. Thepatient support deck, in turn, generally comprises one or more movabledeck sections arranged to support the patient in different positions,such as a Fowler's position. To this end, one or more of the decksections may be designed to pivot relative to the frame.

Depending on the configuration of the patient support apparatus and thephysical characteristics of the patient, it will be appreciated that itcan be difficult for a caregiver to pivot the deck section into anupright position during the process of positioning the patient. Here,the patient support apparatus may be provided with an actuator, such asa gas strut, to assist with pivoting the deck section into the uprightposition. Occasionally, some caregivers may have difficulty overcomingbiasing effects of the gas strut when attempting to pivot the decksection from an upright position into a reclined position. Furthermore,cold weather tends to cause gas struts to exert less biasing force and,in some cases, the caregiver may be required to provide additional forceto pivot the deck section into the upright position.

While patient support apparatuses have generally performed well fortheir intended purpose, there remains a need in the art for a patientsupport apparatus which overcomes the disadvantages in the prior art.

BRIEF DESCRIPTION OF THE DRAWINGS

Advantages of the present invention will be readily appreciated as thesame becomes better understood by reference to the following detaileddescription when considered in connection with the accompanyingdrawings.

FIG. 1A is a perspective view of a patient support apparatus having apatient support deck with a deck section shown in an upright position.

FIG. 1B is another perspective view of the patient support apparatus ofFIG. 1A with the deck section shown in a lowered position.

FIG. 2 is another perspective view of the patient support deck of FIGS.1A-1B, shown with an actuator configured to facilitate movement of thedeck section.

FIG. 3 is an exploded perspective view of the patient support deck andthe actuator of FIG. 2.

FIG. 4 is a perspective view of one embodiment of the actuator of FIGS.2-3 shown with a cover removed.

FIG. 5 is another perspective view of the actuator of FIG. 4 shown witha housing member removed to depict a torque multiplier and a biasingdevice.

FIG. 6A is a side view of the actuator of FIG. 5 shown having a latchmechanism arranged in a disengaged position.

FIG. 6B is another side view of the actuator of FIG. 6A shown with thelatch mechanism arranged in an engaged position.

FIG. 7 is a partial perspective view of another embodiment of anactuator configured to facilitate movement of the deck section of thepatient support deck of FIG. 4.

FIG. 8A is a side view of the actuator of FIG. 7 shown arranged in afirst position.

FIG. 8B is another side view of the actuator of FIG. 8A shown arrangedin a second position.

FIG. 9 is a partial perspective view of another embodiment of anactuator configured to facilitate movement of the deck section of thepatient support deck of FIGS. 1A-1B.

FIG. 10 is a partial perspective view of another embodiment of anactuator configured to facilitate movement of the deck section of thepatient support deck of FIGS. 1A-1B.

DETAILED DESCRIPTION

Referring now to FIGS. 1A-1B, a patient support apparatus 20 is shownfor supporting a patient. In the representative embodiment illustratedherein, the patient support apparatus 20 is realized as a mobile cotthat is utilized to transport patients, such as from an emergency siteto an emergency vehicle (e.g., an ambulance). However, as will beappreciated from the subsequent description below, the patient supportapparatus 20 may comprise a hospital bed, a stretcher, and the like.

The patient support apparatus 20 shown in FIGS. 1A-1B comprises asupport structure 22 that provides support for the patient. In therepresentative embodiment illustrated herein, the support structure 22comprises a movable base 24, a support frame 26, and a patient supportdeck 28. The support frame 26 and the patient support deck 28 are spacedabove the base 24 in FIGS. 1A-1B. As is described in greater detailbelow, the support frame 26 and the patient support deck 28 are arrangedfor movement relative to the base 24.

As is best depicted in FIG. 2, the patient support deck 28 has at leastone deck section 30 arranged for movement relative to the support frame26 to support the patient in different positions, orientations, and thelike. The deck sections 30 of the patient support deck 28 provide apatient support surface 32 upon which the patient is supported. Morespecifically, in the representative embodiment of the patient supportapparatus 20 illustrated herein, the patient support deck 28 has threedeck sections 30 which cooperate to define the patient support surface32: a back section 34, a seat section 36, and a leg section 38. The seatsection 36 is fixed relative to the support frame 26, and the legsection 38 may be fixed or may be movable relative to the support frame26. Other configurations are contemplated.

The base 24, the support frame 26, the patient support deck 28, and thepatient support surface 32 each have a head end and a foot endcorresponding to designated placement of the patient's head and feet onthe patient support apparatus 20. The support frame 26 comprises alongitudinal axis L (see FIG. 2) along its length from the head end tothe foot end. The support frame 26 also comprises a vertical axis Varranged crosswise (e.g., perpendicularly) to the longitudinal axis L,along which the support frame 26 may be lifted and lowered relative tothe base 24. The construction of the support structure 22 may take onany known design, and is not limited to that specifically set forthherein. In addition, a mattress (not shown) may be provided in certainembodiments, such that the patient rests directly on a patient supportsurface of the mattress while also being supported by the patientsupport surface 32.

Side rails (not shown) may be coupled to the support frame 26 in someembodiments. Depending on the specific configuration of the patientsupport apparatus 20, it will be appreciated that there could bedifferent types and/or arrangements of various numbers of side rails.The side rails may be fixed to the support frame 26 or may be movablebetween a raised position in which they block ingress and egress intoand out of the patient support apparatus 20, one or more intermediatepositions, and a lowered position in which they are not an obstacle tosuch ingress and egress. In still other configurations, such as in theillustrated embodiment, the patient support apparatus 20 may not includeany side rails.

Wheels 42 are coupled to the base 24 to facilitate transport over floorsurfaces. The wheels 42 are arranged in each of four quadrants of thebase 24. In the embodiment shown, the wheels 42 are caster wheels ableto rotate and swivel relative to the support structure 22 duringtransport. Each of the wheels 42 forms part of a caster assembly 44, andeach caster assembly 44 is mounted to the base 24. It should beunderstood that various configurations of the caster assemblies 44 arecontemplated. In addition, in some embodiments, the wheels 42 are notcaster wheels and may be non-steerable, steerable, non-powered, powered,or combinations thereof. Additional wheels are also contemplated. Forexample, the patient transport apparatus 20 may comprise fournon-powered, non-steerable wheels, along with one or more poweredwheels.

In other embodiments, one or more auxiliary wheels (powered ornon-powered), which are movable between stowed positions and deployedpositions, may be coupled to the support structure 22. In some cases,when these auxiliary wheels are located between caster assemblies 44 andcontact the floor surface in the deployed position, they cause two ofthe caster assemblies 44 to be lifted off the floor surface therebyshortening a wheel base of the patient transport apparatus 20. A fifthwheel may also be arranged substantially in a center of the base 24. Itwill be appreciated that the patient support apparatus 20 may comprisedifferent support structure 22 configurations to support the supportdeck 28. For example, a stationary hospital bed may comprise a patientsupport deck 28 supported by a support structure 22 that rests directlyon a floor surface without a discrete base 24 or wheels 42. Similarly,it is contemplated that the patient support apparatus 20 could beconfigured without a discrete base 24, such as with wheels 42 coupleddirectly to the support structure 22. Other configurations arecontemplated.

In the embodiment illustrated in FIGS. 1A-2, the deck section 30realized as the back section 34 is arranged for articulation relative tothe support frame 26 between a first position 30A (see FIG. 1A) and asecond position 30B (see FIG. 1B). Here, the back section 34 articulatesbetween the first position 30A and the second position 30B about anarticulation axis A (see FIG. 2). To this end, the back section 34 has apivot end 46 proximal to the articulation axis A, and a free end 48distal from the articulation axis A. The first position 30A, shown inFIG. 1A, is configured to support a patient in a generally uprightposition, such as the Fowler's position. In the first position 30A, thefree end 48 is higher than the pivot end 46. Shown in FIG. 1B, thesecond position 30B is configured to support a patient lying flat. Inthe second position 30B, the free end 48 is generally at the same heightas the pivot end 46. It should be appreciated that the relative heightsof the pivot end 46 and the free end 48 are used herein to differentiatethe first position 30A from the second position 30B with respect to thesupport frame 26, and may be arranged in different ways relative to theenvironment such as if the support deck 28 is tilted in aTrendelenburg's position (not shown). Furthermore, it will beappreciated that the first position 30A and the second position 30B candefined in a number of different ways sufficient to differentiate fromeach other.

In addition to the first position 30A and the second position 30B, thedeck section 30 may be configured to articulate into any number ofintermediate positions to support a patient more upright or lessupright. For example, the back section 34 may be arranged to form a90-degree angle with the other deck sections 36, 38 in the firstposition 30A, and a 0-degree angle in the second position 30B. The backsection 34 may be able to be latched in intermediate positions at15-degrees, 30-degrees, 45-degrees, 60-degrees, etc. Generally, the backsection 34 pivots about the articulation axis A through an arc of atleast 30-degrees between the first position 30A and the second position30B.

Referring now to FIGS. 1A-3, the patient support apparatus 20 furthercomprises deck supports, generally indicated at 50, coupled to each ofthe deck sections 30 and configured to mount the respective decksections 30 to the support frame 26. In FIGS. 2-3, the support frame 26is omitted from view to help illustrate how the deck supports 50 arecoupled to the deck sections 30. Each deck support 50 comprises arespective lateral portion 52 extending between right and left framemembers 40A, 40B (or “rails”) of the support frame 26. A deck coupler 54is provided to facilitate articulation of the back section 34 relativeto the support frame 26. The deck coupler 54 is disposed at the pivotend 46 of the back section 34 and couples the back section 34 to thesupport frame 26. In the embodiment shown, the deck coupler 54 iscoupled to the deck support 50 and supports the deck section 30 forrotation about the articulation axis A.

The patient support apparatus 20 further comprises an actuator 56interposed in force-translating relation between the support frame 26and the back section 34. The actuator 56 is coupled to the support frame26 and is configured to store energy in response to articulation of theback section 34 from the first position 30A toward the second position30B. The stored mechanical energy may then be released to urge the backsection 34 back toward the first position 30A. In the embodiment shown,the patient support apparatus 20 is equipped with two actuators 56: oneactuator 56 coupled to each of the right and left sides of the supportframe 26, respectively corresponding to the right frame member 40A andthe left frame member 40B. However, it is contemplated that the patientsupport apparatus 20 may have only a single actuator 56, such ascentered between the left and right sides or offset toward one of thesides. Furthermore, it will be appreciated that more than two actuators56 may be utilized in some embodiments, depending on the specificconfiguration of the patient support apparatus. Moreover, where morethan one of the deck sections 30 is movable, the patient supportapparatus 20 may comprise one or more actuators 56 for each movable decksection 30. Other configurations are contemplated.

Referring now to FIGS. 4-6B, a first embodiment of the actuator 56 isshown. The actuator 56 comprises a biasing device 58 (see FIG. 5) havingan interface 60, and a torque multiplier 62 coupled to the back section34. As is described in greater detail below, the biasing device 58 isconfigured to store mechanical energy via the interface 60, and thetorque multiplier 62 is engaged with the interface 60 to translatemechanical energy stored in the biasing device 58 into force acting onthe back section 34 to urge the back section 34 toward the firstposition 30A. When the back section 34 is articulated from the firstposition 30A toward the second position 30B, mechanical energy istranslated through the torque multiplier 62 and is stored in the biasingdevice 58. Conversely, mechanical energy stored in the biasing device 58is translated through the torque multiplier 62 into force acting towardthe back section 34 to urge the back section 34 toward the firstposition 30A from the second position 30B.

The actuator 56 further comprises a cover 64 defining an interior. Thecover 64 is arranged such that the biasing device 58 and the torquemultiplier 62 are disposed within the interior. The cover 64 helpsprevent ingress of foreign objects, the presence of which may otherwiseimpair operation by becoming stuck in the actuator 56. The cover 64 alsohelps prevent a patient or caregiver from accessing the interior duringuse of the patient support apparatus 20.

Referring specifically to FIGS. 4 and 5, the actuator 56 comprises firstand second housing members 68A, 68B. The housing members 68A, 68B arecoupled to the support frame 26 and support the various components ofthe actuator 56. The housing members 68A, 68B are spaced from eachother, with the biasing device 58 and the torque multiplier 62 disposedtherebetween. Shafts 70 extend between each of the housing members 68A,68B to rotatably support the torque multiplier 62 and the biasing device58.

The biasing device 58 comprises a resiliently flexible biasing element72 coupled to the interface 60. In the representative embodimentillustrated in FIGS. 6A-6B, the biasing element 72 is realized as aspiral torsion spring. However, as will be appreciated from thesubsequent description below, the biasing element 72 could be configuredin a number of different ways sufficient to resiliently deform to storemechanical energy as the deck section 30 moves from the first position30A to the second position 30B. The biasing element 72 has a firstspring end 74 fixedly coupled to one of the housing members 68A, and asecond spring end 76 movable relative to the first spring end 74. In theillustrated embodiment, the biasing element 72 stores mechanical energyby winding the second spring end 76 about one of the shafts 70. Here,the second spring end 76 is coupled to the interface 60 of the biasingdevice 58 such that the interface 60 winds the second spring end 76. Theinterface 60 of the biasing device 58 may comprise a pinion gear 78engaged with the second spring end 76. The pinion gear 78 is rotatablysupported on the shaft 70 such that rotation of the pinion gear 78 windsor unwinds the second spring end 76.

The torque multiplier 62 may comprise a drive gear 80 having a toothedportion with gear teeth 82 and a pin boss 84. The drive gear 80 isrotatably supported on one of the shafts 70 and is disposed in meshedengagement with the pinion gear 78. Put differently, the drive gear 80engages the pinion gear 78 in rotational communication such thatrotation of the drive gear 80 facilitates rotation of the interface 60,and vice versa. It should be appreciated that the torque multiplier 62may transfer mechanical energy to the biasing device 58 in differentways, such as without the use of a drive gear 80 or a pinion gear 78.For example, the torque multiplier may comprise a belt and pulleyarrangement. Other configurations are contemplated.

Generally, the pinion gear 78 rotates at a rate greater than the drivegear 80. Each of the pinion gear 78 and the drive gear 80 have arespective size defined by a diameter measurement, or a number of teeth.The drive gear 80 has a drive gear size and the pinion gear 78 has apinion gear size. The drive gear 80 and the pinion gear 78 rotate at aratio of the drive gear size to the pinion gear size. The ratio of thedrive gear size to the pinion gear size may be 6:1. The ratio isgenerally greater than 1:1 such that the pinion gear 78 rotates fasterthan the drive gear 80. Other ratios are possible, such as 1:1, 2:1,3:1, etc.

The torque multiplier 62 further comprises a link 86 to transmit forcebetween the drive gear 80 and the back section 34. The link 86 has afirst link end 88 rotatably coupled to the back section 34 (e.g. via apivot pin), and a second link end 90 rotatably coupled to the pin boss84. The first link end 88 is spaced from the second link end 90.Movement of the back section 34 transfers force to the drive gear 80 viathe link 86, thereby causing the drive gear 80 to rotate. Likewise,rotation of the drive gear 80 transfers force to the link 86 to move theback section 34.

The patient support apparatus 20 further comprises a latch mechanism 92coupled to the actuator 56. The latch mechanism 92 is arranged forselective engagement with the torque multiplier 62 and is movablebetween an engaged position 92A (see FIG. 6B), and a disengaged position92B (see FIG. 6A). In the engaged position 92A, the latch mechanism 92restricts articulation of the back section 34. Conversely, in thedisengaged position 92B, the latch mechanism 92 allows the back section34 to articulate. To this end, the latch mechanism 92 comprises a cam 93and a pawl 94. The pawl 94 is pivotably coupled to the housing member68A (e.g. via a pivot pin) and has pawl teeth selectively engageablewith the gear teeth 82 of the drive gear 80. In the engaged position92A, the cam 93 forces the pawl 94 into engagement with the gear teeth82 to prevent rotation of the drive gear 80. In the disengaged position92B, the cam 93 allows the pawl 94 to move away from and out ofengagement with the gear teeth 82, thereby allowing the drive gear 80 torotate.

The caregiver can move the latch mechanism 92 between the engagedposition 92A and the disengaged position 92B via a lever 95 (see FIGS.1A and 1B) that is operatively coupled to the cam 93. The lever 95 maybe located either remotely from the cam 93, or may be directly coupledto the cam 93. In one embodiment, the lever 95 is mounted to the supportframe 26. A cable 96 may be coupled to the lever 95 and to the cam 93such that movement of the lever 95 applies tension to the cable 96 usedto actuate the cam 93. Alternatively, the cam 93 may be actuated by alinkage, an electrical motor, a solenoid, and other types of actuatorsknown in the art. The latch mechanism 92 further comprises a cam biasingdevice, such as a spring 97 that biases the cam 93 toward the engagedposition 92A. Other configurations are contemplated.

When the back section 34 is in the first position 30A, the caregiver maywish to lower the back section 34 into the second position 30B. To thisend, the caregiver can move the latching mechanism 92 into thedisengaged position 92B by engaging the lever 95. Here, the lever 95tensions the cable 96 which, in turn, moves the cam 93 and disengagesthe pawl 94 from the drive gear 80. When the latch mechanism 92 is inthe disengaged position 92B, the back section 34 can be moved toward thesecond position 30B. To this end, the caregiver can apply force to thefree end 48 of the back section 34 so as to articulate the back section34 about the articulation axis A, which transfers force to the torquemultiplier 62. The torque multiplier 62, in turn, translates the forceacting on the back section 34 into rotation of the drive gear 80 via thelink 86. Here, rotation of the drive gear 80 is transferred to thebiasing device 58 via the interface 60; the drive gear 80 rotates thepinion gear 78 which, in turn, winds the second end 76 of the biasingelement 72 to store mechanical energy in the biasing device 58. When theback section 34 reaches the desired second position 30B, the caregivercan then move the latching mechanism 92 to the engaged position 92B toprevent subsequent inadvertent movement of the back section 34 away fromthe second position 30B.

When the back section 34 is in the second position 30B, the caregivermay wish to raise the back section 34 into the first position 30A. Tothis end, the caregiver can move latching mechanism 92 into thedisengaged position 92B by engaging the lever 95. Here, the lever 95tensions the cable 96 which, in turn, moves the cam 93 and disengagesthe pawl 94 from the drive gear 80. With the latch mechanism 92 is inthe disengaged position 92B, mechanical energy stored in the biasingdevice 58 is released and translates through the torque multiplier 62 tomove the back section 34 toward the first position 30A. To this end, thesecond end 76 of the biasing element 72 rotates the pinion gear 78 torotate the drive gear 80. The drive gear 80 rotates more slowly than thepinion gear 78, as noted above, which slows or otherwise limits the rateat which the back section 34 articulates toward the first position 30Aas the torque multiplier 62 translates the mechanical energy stored inthe biasing device 58 into force acting on the back section 34 to urgethe free end 48 upward. When the back section 34 reaches the desiredfirst position 30A, the caregiver can then move the latching mechanism92 to the engaged position 92B to prevent subsequent inadvertentmovement of the back section 34 away from the first position 30A. Itshould be appreciated that the preceding description of the operation ofthe actuator 56 is not limited to operation between the first position30A and the second position 30B, but any of the intermediate positionsdepending on the direction that the caregiver desires to move the backsection 34.

Turning now to FIGS. 4 and 7-8B, a second embodiment of the actuator 156is shown. This embodiment is similar to the embodiment of the actuator56 described above, and likewise comprises a biasing device 158 havingan interface 160, and a torque multiplier 162 coupled to the backsection 34. The biasing device 158 is similarly configured to storemechanical energy via the interface 160, and the torque multiplier 162is engaged with the interface 160 to translate mechanical energy storedin the biasing device 158 into force acting on the back section 34 tourge the back section 34 toward the first position 30A. Here too, whenthe back section 34 is articulated toward the second position 30B,mechanical energy is translated through the torque multiplier 162 and isstored in the biasing device 158, and mechanical energy stored in thebiasing device 158 is likewise translated through the torque multiplier162 into force acting toward the back section 34 to urge the backsection 34 toward the first position 30A.

In this embodiment, the actuator 156 likewise comprises first and secondhousing members 168A, 168B. The housing members 168A, 168B are coupledto the support frame 26 to support the actuator 156. The housing members168A, 168B are spaced from each other with the biasing device 158 andthe torque multiplier 162 disposed therebetween. Here too, a shaft 170extends between each of the housing members 168A, 168B to rotatablysupport the torque multiplier 162 and the biasing device 158. Likewise,the biasing device 158 further comprises at least one resilientlyflexible biasing element 172 coupled to the interface 160. The biasingelement 172 may be a spiral torsion spring, such as shown in FIGS. 8Aand 8B. The biasing element 172 has a first spring end 174 fixedlycoupled to one of the housing members 168A, and a second spring end 176movable relative to the first spring end 174. The biasing element 172stores mechanical energy by winding the second spring end 176 on theshaft 170. The second spring end 176 is coupled to the interface 160 ofthe biasing device 158 such that the interface 160 winds the secondspring end 176.

In the second embodiment of the actuator 156, the interface 160 of thebiasing device 158 comprises a sun gear 200, and the torque multiplier162 comprises a ring gear 202, planet gears 204, and a planet carrier206. The sun gear 200 rotates about the same shaft 170 as the secondspring end 176 to wind the second spring end 176. The planet gears 204are arranged between and are engaged with the ring gear 202 and the sungear 200 such that the sun gear 200, the planet gears 204, and the ringgear 202 define a planetary gearset 208. The planetary gearset 208translates mechanical energy stored in the biasing device 158 into forceacting on the back section 34 to urge the back section 34 toward thefirst position 30A. The planetary gearset 208 has a planetary reductionratio of 6:1 such that the sun gear 200 rotates faster than the planetcarrier 206. However, other ratios are contemplated, such as 1:1, 2:1,3:1, etc.

The planet carrier 206 comprises a radially extending arm portion 210that serves as a crank. The torque multiplier 162 further comprises alink 186 to transmit force between the biasing device 158 and the backsection 34. The link 186 has a first link end 188 spaced from a secondlink end 190. The first link end 188 is rotatably coupled to the backsection 34, and the second link end 190 is rotatably coupled to the armportion 210 of the planet carrier 206 (see FIG. 7). Movement of the backsection 34 transfers force via the link 186 to the arm portion 210,which causes the planet carrier 206 to rotate. Likewise, rotation of theplanet carrier 206 moves the arm portion 210 and transfers force to thelink 186 to move the back section 34.

Similar to the first embodiment of the actuator 56 described above, thepatient support apparatus 20 may comprises a latch mechanism 192 coupledto the second embodiment of the actuator 156. In this embodiment, thelatch mechanism 192 is similarly arranged for selective engagement withthe torque multiplier 162 and is movable between an engaged position anda disengaged position (not shown in detail). In the engaged position,the latch mechanism 192 restricts articulation of the back section 34.Conversely, in the disengaged position, the latch mechanism 192 allowsthe back section 34 to articulate. To this end, the latch mechanism 192comprises a pawl 194, and a detent wheel 212 coupled to the arm portion210. The pawl 194 is pivotably coupled to the housing member 168A (e.g.via a pivot pin) and has pawl teeth selectively engageable with thedetent wheel 212. In the engaged position, the pawl teeth mesh with thedetent wheel 212 to prevent rotation of the planet carrier 206. In thedisengaged position, the pawl 194 is spaced from and is out ofengagement with the detent wheel 212, thereby allowing the planetcarrier 206 to rotate.

The caregiver can move the latch mechanism 192 between the engagedposition and the disengaged position by engaging the lever 95 (see FIGS.1A and 1B) which, in this embodiment, is likewise operatively coupled tothe pawl 194. The lever 95 may be located either remotely from the cam93, or directly coupled to the pawl 194. In one embodiment, the lever 95is mounted to the support frame 26. A cable 196 may be coupled to thelever 95 and to the pawl 194 such that movement of the lever 95 appliestension to the cable 196 to actuate the pawl 194. Alternatively, thepawl 194 may be actuated by a linkage, an electrical motor, a solenoid,and other actuators known in the art. The latch mechanism 192 furthercomprises a pawl biasing device, such as a spring 197 that biases thepawl 194 toward the engaged position. Other configurations arecontemplated.

When the back section 34 is in the first position 30A, the caregiver maywish to lower the back section 34 into the second position 30B. To thisend, the caregiver can move the latching mechanism 192 into thedisengaged position by engaging the lever 95. Here, the lever 95tensions the cable 196 which, in turn, causes the pawl 194 to disengagefrom the detent wheel 212. When the latch mechanism 192 is disengaged,the back section 34 can be moved toward the second position 30B. To thisend, the caregiver can apply force to the free end 48 of the backsection 34 to articulate the back section 34 about the articulation axisA, which transfers force to the torque multiplier 162. The torquemultiplier 162, in turn, translates the force acting on the back section34 into rotation of the planet carrier 206 via the link 186. Here,rotation of the planet carrier 204 is transferred to the biasing device158 via the interface 160; the planet carrier 206 rotates the planetgears 204 which, in turn, rotate the sun gear 200 to wind the second end176 of the biasing element 172 to store mechanical energy in the biasingdevice 158. When the back section 34 reaches the desired second position30B, the caregiver can then move the latching mechanism 192 to theengaged position to prevent subsequent inadvertent movement of the backsection 34 away from the second position 30B.

When the back section 34 is in the second position 30B, the caregivermay wish to raise the back section 34 into the first position 30A. Tothis end, the caregiver can move the latching mechanism 192 into thedisengaged position by engaging the lever 95. Here, the lever 95tensions the cable 196 which, in turn, disengages the pawl 194 from thedetent wheel 212. When the latch mechanism 192 is disengaged, mechanicalenergy stored in the biasing device 158 is released and translatesthrough the torque multiplier 162 to move the back section 34 toward thefirst position 30A. To this end, the second end 176 of the biasingelement 172 rotates the sun gear 200 to rotate the planet gears 204 andthe planet carrier 206. The planet carrier 206 rotates more slowly thanthe sun gear 200, which slows or otherwise limits the rate at which theback section 34 articulates toward the first position 30A as the torquemultiplier 162 translates the mechanical energy stored in the biasingdevice 158 into force acting on the back section 34 to urge the free end48 upward. When the back section 34 reaches the desired first position30A, the caregiver can move the latching mechanism 192 to the engagedposition to prevent subsequent inadvertent movement of the back section34 away from the first position 30A. Here too, it should be appreciatedthat the preceding description of the operation of the actuator 156 isnot limited to operation between the first position 30A and the secondposition 30B, but any of the intermediate positions depending on thedirection that the caregiver desires to move the back section 34.

Turning now to FIG. 9, a third embodiment of the actuator 256 is shown.Similar to the first and second embodiments of the actuator 56, 156described above, the third embodiment of the actuator 256 also comprisesa biasing device 258 having an interface 260. The biasing device 258 islikewise configured to store and translate mechanical energy into forceacting on the back section 34 to urge the back section 34 toward thefirst position 30A. Here too, when the back section 34 is articulatedtoward the second position 30B, mechanical energy is translated andstored in the biasing device 258. Conversely, mechanical energy storedin the biasing device 258 as the back section 34 is moved to the secondposition 30B is translated into force acting on the back section 34 tourge the back section 34 back toward the first position 30A.

The biasing device 258 further comprises a resiliently flexible biasingelement 272 coupled to the interface 260. The biasing element 272 may bea torsion spring that has a first spring end 274 coupled to the supportframe 26, and a second spring end 276 coupled to the interface 260 andmovable relative to the first spring end 274. In this embodiment, theinterface 260 comprises a spring retainer 300 coupled to the backsection 34, and is movable with the back section 34 to move the secondspring end 276 relative to the first spring end 274.

The actuator 256 may further comprise a damper 302 coupled to thebiasing device 258 which is configured to retard translation ofmechanical energy stored in the biasing device 258 to the back section34, such as when the back section 34 articulates from the first position30A to the second position 30B. The damper 302 is coupled between thedeck coupler 54 and the support frame 26, and prevents the back section34 from articulating between the second position 30B and the firstpositon 30A too rapidly. The damper 302 exerts increasing damping forceas the back section 34 articulates at increasing rates, therebyretarding the translation of mechanical energy. A detent mechanism (notshown) may be provided to latch the back section 34 in the secondposition 30B. The detent mechanism may further be configured to latchthe back section 34 in intermediate positions between the first position30A and the second position 30B.

Turning now to FIG. 10, a fourth embodiment of the actuator 356 isshown. Similar to the previous embodiments of the actuator 56, 156, 256described above, the fourth embodiment of the actuator 356 alsocomprises a biasing device 358 having an interface 360. The biasingdevice 358 is likewise configured to store and translate mechanicalenergy into force acting on the back section 34 to urge the back section34 toward the first position 30A. Here too, when the back section 34 isarticulated toward the second position 30B, mechanical energy istranslated and stored in the biasing device 358. Conversely, mechanicalenergy stored in the biasing device 358 when the back section 34 ismoved to the second position 30B is translated into force acting on theback section 34 to urge the back section 34 toward the first position30A.

The biasing device 358 further comprises a resiliently flexible biasingelement 372 coupled to the interface 360. The biasing element 372 may bean extension spring that has a first spring end 374 coupled to thesupport frame 26, and a second spring end 376 coupled to the interface360 and movable relative to the first spring end 374. In thisembodiment, the interface 360 comprises a spring retainer 400 coupled tothe back section 34, and is movable with the back section 34 to move thesecond spring end 376 relative to the first spring end 374.

The actuator 356 may further comprise a damper 402 coupled to thebiasing device 358 which is configured to retard translation ofmechanical energy stored in the biasing device 358 to the back section34, such as when the back section 34 articulates between the firstposition 30A and the second position 30B. The damper 402 is coupledbetween the deck coupler 54 and the support frame 26, and prevents theback section 34 from articulating from the second position 30B to thefirst positon 30A too rapidly. Here too, the damper 402 exertsincreasing damping force as the back section 34 articulates atincreasing rates, thereby retarding the translation of mechanicalenergy. A detent mechanism (not shown) may be provided to latch the backsection 34 in the second position 30B. The detent mechanism may befurther be configured to latch the back section 34 in intermediatepositions between the first position 30A and the second position 30B.

It will be further appreciated that the terms “include,” “includes,” and“including” have the same meaning as the terms “comprise,” “comprises,”and “comprising.” Moreover, it will be appreciated that terms such as“first,” “second,” “third,” and the like are used herein todifferentiate certain structural features and components for thenon-limiting, illustrative purposes of clarity and consistency.

Several configurations have been discussed in the foregoing description.However, the configurations discussed herein are not intended to beexhaustive or limit the invention to any particular form. Theterminology which has been used is intended to be in the nature of wordsof description rather than of limitation. Many modifications andvariations are possible in light of the above teachings and theinvention may be practiced otherwise than as specifically described.

The invention is intended to be defined in the independent claims, withspecific features laid out in the dependent claims, wherein thesubject-matter of a claim dependent from one independent claim can alsobe implemented in connection with another independent claim.

What is claimed is:
 1. A patient support apparatus for supporting apatient, said patient support apparatus comprising: a support frame; asupport deck coupled to said support frame and having a deck sectionarranged to articulate relative to said support frame between a firstposition and a second position; an actuator interposed inforce-translating relation between said support frame and said decksection, said actuator comprising; a biasing device configured to storemechanical energy and having an interface, and a torque multipliercoupled to said deck section and engaged with said interface totranslate mechanical energy stored in said biasing device into forceacting on said deck section to urge said deck section toward said firstposition.
 2. The patient support apparatus according to claim 1, whereinsaid actuator is configured such that mechanical energy is stored insaid biasing device in response to articulation of said deck sectiontoward said second position, and such that mechanical energy stored insaid biasing device is translated into force acting toward said decksection to urge said deck section toward said first position.
 3. Thepatient support apparatus according to claim 2, wherein said interfacecomprises a pinion gear; and wherein said torque multiplier comprises adrive gear disposed in rotational communication with said pinion gear.4. The patient support apparatus according to claim 3, wherein saiddrive gear has a drive gear size, said pinion gear has a pinion gearsize, and a ratio of said drive gear size to said pinion gear size isgreater than 1:1.
 5. The patient support apparatus according to claim 3,wherein said torque multiplier further comprises a link to transmitforce between said drive gear and said deck section, said link having afirst link end and a second link end with said first link end rotatablycoupled to said deck section and with said second link end rotatablycoupled to said drive gear.
 6. The patient support apparatus accordingto claim 3, further comprising a latch mechanism coupled to saidactuator and arranged for selective engagement with said torquemultiplier to restrict articulation of said deck section.
 7. The patientsupport apparatus according to claim 6, wherein said drive gearcomprises gear teeth, and wherein said latch mechanism comprises a pawlselectively engageable with said gear teeth of said drive gear toprevent rotation of said drive gear.
 8. The patient support apparatusaccording to claim 2, wherein said interface comprises a sun gear; andwherein said torque multiplier comprises a ring gear and planet gears,wherein said planet gears are arranged between and engaged with saidring gear and said sun gear such that said sun gear, said planet gears,and said ring gear define a planetary gearset to translate mechanicalenergy stored in said biasing device into force acting on said decksection to urge said deck section toward said first position.
 9. Thepatient support apparatus according to claim 8, wherein said torquemultiplier further comprises a link to transmit force between saidplanetary gearset and said deck section, said link having a first linkend and a second link end with said first link end rotatably coupled tosaid deck section and with said second link end rotatably coupled tosaid planetary gearset.
 10. The patient support apparatus according toclaim 8, further comprising a latch mechanism coupled to said actuatorand arranged for selective engagement with said torque multiplier torestrict articulation of said deck section.
 11. The patient supportapparatus according to claim 1, wherein said biasing device furthercomprises a resiliently flexible biasing element coupled to saidinterface.
 12. The patient support apparatus according to claim 11,wherein said actuator further comprises a housing coupled to saidsupport frame with said housing rotatably supporting said torquemultiplier.
 13. The patient support apparatus according to claim 12,wherein said biasing element of said biasing device comprises a torsionspring having a first spring end and a second spring end with said firstspring end coupled to said housing and with said second spring endcoupled to said interface.
 14. The patient support apparatus accordingto claim 1, wherein said deck section is arranged for articulationbetween said first position and said second position about anarticulation axis.
 15. The patient support apparatus according to claim14, wherein said deck section comprises a deck coupler rotatably fixedto said support frame and supporting said deck section for rotationabout said articulation axis.
 16. The patient support apparatusaccording to claim 14, wherein said deck section is arranged to pivotabout said articulation axis through an arc of at least 30 degreesbetween said first position and said second position.
 17. The patientsupport apparatus according to claim 14, wherein said torque multiplierfurther comprises a link to transmit force between said biasing deviceand said deck section, said link having a first link end and a secondlink end with said first link end rotatably coupled to said deck sectionand with said second link end operably coupled to said interface suchthat said first link end is spaced from said second link end.
 18. Apatient support apparatus for supporting a patient, said patient supportapparatus comprising: a support frame; a support deck coupled to saidsupport frame and having a deck section arranged to articulate relativeto said support frame between a first position and a second position; anactuator interposed in force-translating relation between said supportframe and said deck section, said actuator comprising; a biasing deviceconfigured to store mechanical energy and having an interface totranslate mechanical energy stored in said biasing device into forceacting on said deck section to urge said deck section toward said firstposition.
 19. The patient support apparatus according to claim 18,wherein said biasing device comprises a spring having a first spring endand a second spring end, and said interface comprises a spring retainer,with said first spring end being coupled to said support frame and saidsecond spring end being coupled to said interface.
 20. The patientsupport apparatus according to claim 18, wherein said actuator furthercomprises a damper coupled to said biasing device and configured toretard translation of mechanical energy stored in said biasing device tosaid deck section as said deck section articulates between said firstposition and said second position.